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To:	cygwin AT cygwin DOT com
From:	"Alex Vinokur" <alexvn AT users DOT sourceforge DOT net>
Subject:	Behavior of ifstream::read() in g++
Date:	Sun, 15 Oct 2006 06:10:17 +0200
Lines:	81
Message-ID:	<egscaa$5sd$1@sea.gmane.org>
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This program has different behavior in
* g++ 3.4.4 (Cygwin)
* gpp 4.0.1 *Djgpp)
* Microsoft C++ 13.00.9466

------- foo.cpp ------
#include <iostream>
#include <iomanip>
#include <fstream>
using namespace std;

#define BUFFER_SIZE  1500
#define INPUT_FILE_NAME  "in.txt"

void foo ()
{
char cbuffer[BUFFER_SIZE];
ifstream fs (INPUT_FILE_NAME);

  fs.clear();
  fs.seekg (0, ios::beg);

  while (!fs.eof())
  {
    fs.read (cbuffer, sizeof(cbuffer));
    cout << "rdstate() = 0x" << hex << fs.rdstate() << dec << "; gcount() = " << fs.gcount() << endl;
  }
  cout << "rdstate() = 0x" << hex << fs.rdstate() << dec << endl;
}

int main ()
{
  foo ();
  return 0;
}

----------------------


Test input file can be seen at
http://groups.google.com/group/test-av/msg/0c4d3da487594ab7


Output for g++ (Cygwin)
--------------------
rdstate() = 0x6; gcount() = 1499
rdstate() = 0x6
-------------------
It seems that behavior of g++ is wrong here.


Output for gpp (Djgpp)
-------------------
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x6; gcount() = 1071
rdstate() = 0x6
-------------------


Output for Microsoft C++
-------------------
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x0; gcount() = 1500
rdstate() = 0x3; gcount() = 1071
rdstate() = 0x3
-------------------

 Alex Vinokur
     email: alex DOT vinokur AT gmail DOT com
     http://mathforum.org/library/view/10978.html
     http://sourceforge.net/users/alexvn





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